Chapter 1: General Registration Information. An RV Bill of Sale is a legal document that serves as proof of the sale and transfer of ownership of a recreational vehicle (RV) from a seller to a buyer.A California motor vehicle bill of sale is part of the vehicle registration process. Use a free template to write your own bill of sale. Get the buyer, seller, and witnesses to sign the bill. At the bottom of the form, leave spaces for the buyer's and seller's signatures. A Recreational Vehicle (RV) Bill of Sale is required anytime an RV is sold or transferred between a seller and a buyer.